For the past several decades, practioners in the offshore art have endeavored to develop commercially acceptable techniques for the fabrication of offshore structures, utilizing what is termed an "integrated deck".
An integrated deck comprises a pre-assembled deck structure which is operable to be installed in one piece on a substructure, such as a steel "jacket" or a concrete gravity base.
A steel "jacket" comprises a framework which is anchored to a submerged surface, conventionally by piling which may pass through the jacket legs or other cylinders carried by the jacket. A gravity base platform may or may not be pile-connected to a submerged surface but is sufficiently heavy such that its own weight or "gravity" provides a significant anchoring force.
In any event, the concept now under consideration pertains similarly to technique for installing an integrated deck on the top of a previously installed substructure.
Prior efforts in this art or in the bridge construction art, and pertaining to deck setting, are generally exemplified by the following disclosures:
__________________________________________________________________________ Patent/Country/Issue or Publication Date Patentee Subject Matter __________________________________________________________________________ 36,606/U.S./Oct. 7, 1862 DuBois Bridge arch set by barge 2,210,408/U.S./Aug. 6, 1940 Henry Deck with diagonal under framing 2,475,933/U.S./July 12, 1949 Woolslayer et al Skid-off deck installation 2,771,747/U.S./Nov. 27, 1956 Rechtin Jack-up deck 2,817,212/U.S./Dec. 24, 1957 Stubbs Tensioned cable with shock absorbers for supporting deck on barge 2,881,590/U.S./Apr. 14, 1959 Zaskey Yieldable rockers supporting deck on barge 2,907,172/U.S./Oct. 6, 1959 Crake Alignment cables between deck and sub- structure, with deck lowered on shock absorbing rams and fenders between deck supporting barge and substructure 2,940,266/U.S./June 14, 1960 Smith Deck ballasted down to substructure 2,979,910/U.S./Apr. 18, 1961 Crake substructure maneuvered by vessel 3,011,318/U.S./Dec. 5, 1961 Ashton Deck supporting barge rapidly ballasted down 3,078,680/U.S./Feb. 26, 1963 Wepsala Deck lowering yoke on vessel 3,857,247/U.S./Dec. 31, 1974 Phares Deck lifting rods on substructure 3,876,181/U.S./Apr. 8, 1975 Lucas Deck elevating jack- up legs coact with substructure 4,002,038/U.S./Jan. 11, 1977 Phares Deck set with derrick 4,012,917/U.S./Mar. 22, 1977 Gendron Deck set with derrick 1,190/697/U.K./May 6, 1970 Global Mating sockets between Marine lowered deck and substructure 1,220,689/U.K./Jan. 27, 1971 Netherlands Dual barges to lower Offshore Co. deck to submerged substructure 1,380,586/U.K./Jan. 15, 1975 Redpath Deck lifted on Dorman Long platform 1,382,118/U.K./Jan. 29, 1975 Redpath Deck lifted on Dorman Long platform 1,419,266/U.K./Dec. 24, 1975 Redpath Substructure Dorman Long maneuvered by vessel 1,430,084/U.K./Mar. 31, 1976 Redpath Deck lowered onto Dorman Long submerged substructure 1,466,279/U.K./Mar. 2, 1977 A/S Akers Mek Jacks or barge to Verksted lower deck 1,469,490/U.K./Apr. 6, 1977 Raymond Int. Deck elevated on substructure 6,713,706/Dutch/Apr. 11, 1969 Netherlands Arch deck supported Offshore Co. on two barges and lowered so as to overhang substruc- ture __________________________________________________________________________
Whatever may be said with respect to the state of the art as exemplified by these prior art patent disclosures, the present invention is directed to significantly advancing the efficacy and reliability of methods and apparatus involved in the handling and installation of integrated deck structures.
One independently significant aspect of the invention relates to methods and apparatus which are designed to effect net reductions in the overall weight of integrated deck units and provide effective, lateral force transmission across a vessel passageway defined by the upper portion of a completed installation.
In a method sense, this first method aspect of the invention may be characterized as follows:
A method of erecting an offshore structure comprising: PA0 said method being characterized by:
transportable substructure means connected with a submerged surface and including
a slotted upper end defining a vessel passage way; PA1 to be supported on vessel means for transportation to the vicinity of said substructure means, with said vessel means moving into said passage way so as to position said integrated deck means generally above said substructure means and in alignment therewith; PA1 causing said vessel means to lower said integrated deck means onto the top of said substructure means and form said offshore structure; and PA1 providing in said offshore structure, comprising said interconnected substructure means and integrated deck means, with PA1 substructure means; PA1 integrated deck means; and PA1 transfer means operable to effect engagement between said integrated deck means and said substructure means, and transfer said integrated deck means from a floating vessel means to said substructure means; PA1 yieldable means carried by at least one of said substructure means and said integrated deck means and operable to PA1 providing substructure means, connected with a submerged surface; PA1 supporting an integrated deck means on vessel means; PA1 moving said vessel means so as to position said integrated deck means over said substructure means; PA1 lowering said integrated deck means at a first, relatively slower transfer rate so as to transfer the load of said integrated deck means from said vessel means to said substructure means; and PA1 thereafter separating previously engaged portions of said vessel means and said integrated deck means at a second, relatively more rapid rate, thereby reducing tendencies for wave actioninduced forces and movements to cause damage to said integrated deck means and vessel means.
providing integrated deck means operable
lateral force transmitting means PA2 provide yieldable, horizontal shock absorbing action directly between said integrated deck means and said substructure means during their mutual engagement, PA2 provide yieldable, vertical shock absorbing action between said integrated deck means and said substructure means during their mutual engagement, PA2 provide motion dampening of said integrated deck means, and PA2 tend to effect a generally desired alignment between mutually engageable portions of said substructure means and said integrated deck means during transfer of said integrated deck means from said vessel means to said substructure means.
carried by one of said substructure means and said integrated deck means, PA3 defining lateral force transmitting, arch-like means extending tranversely from opposite sides of said vessel passageway, generally across at least side portions of said vessel passageway to an intermediate portion of one of said jacket means and integrated deck means, and PA3 at least partially extending across said vessel means while said integrated deck means is supported thereon and said vessel means is in said passageway
said lateral force transmitting means extending laterally beyond side portions of said vessel means, with outer portions thereof being disengaged therefrom when said integrated deck means is supported thereon, and said vessel means is disposed in said passageway.
This first aspect of the invention also involves apparatus means for implementing the method steps which characterize the method aspect set forth above, as well as various refinements of the basic concept, as described in claims hereinafter set forth.
A second independently significant aspect of the invention relates to methods and apparatus which are designed to concurrently effect vertical and horizontal shock absorbing action, wave action induced motion dampening, and desired alignment, as an integrated deck is being installed on a substructure.
In a method sense, this second independently significant aspect of the invention may be defined as follows:
A method of erecting an offshore structure comprising:
said method being characterized by the provision in said transfer means of;
This second aspect of the invention also involves apparatus means for implementing the method steps which characterize the second method aspect set forth above and various refinements of the basic concept, as described in claims hereafter.
A third, independently significant method aspect of the invention involves a method for effecting the installation of an integrated deck on a substrate in two stages, with a second stage thereof involving materially more rapid lowering movement rather than the first stage for the purpose of effecting rapid separation of the integrated deck and a vessel which buoyantly supports the integrated deck.
In relation to method features of this third aspect of the invention, the following description is in order:
A method of forming an offshore structure comprising:
This third aspect of the invention also involves apparatus means for implementing the method steps which characterize the third method aspect set forth above and various refinements of the basic concept, as described in claims hereafter.
As will be recognized, a fourth independently significant aspect of the invention relates to various permutations and combinations of the method and apparatus aspects noted above, including the specific refinements and embellishments described and claimed thereinafter.
In describing the inventions, reference will be made to certain presently preferred embodiments, keeping in mind that such descriptions are intended to be by way of example but not by way of limitation with respect to the overall inventive concepts as herein presented.
In describing these preferred embodiments, reference will be made to the appended drawings.